PROJECT SUMMARY: Osteonecrosis of the femoral head, a disease which usually progresses to arthritis, is newly diagnosed in 10?30,000 patients each year. The treatment for end?stage disease is total hip replacement. Few approaches have been developed to prevent or treat osteonecrosis to delay or eliminate the need for total hip replacement. At this time there is no cure or treatment that has been found to be 100% effective in altering the progression of this disease. The most common treatment in the early stages of the disease, core decompression, creates a drill tract in the femoral head. The clinical results for this procedure have been quite variable. There has been increasing interest in the use of bone marrow aspirates to augment core decompression. However, the studies to date have been limited to case series (no controls) or relatively small numbers of patients. A randomized control trial (RCT) is needed to obtain a more definitive answer as to efficacy of concentrated autologous bone marrow aspirates with core decompression for the treatment of early stage osteonecrosis. The overall goal of our planned multicenter clinical trial (U01) is to test the hypothesis: ?Patients undergoing core decompression augmented with concentrated bone marrow aspirate grafting will have better clinical and radiological outcomes than patients undergoing core decompression alone.? Furthermore, the proposed randomized controlled study will define specific patient characteristics that may influence the long?term outcome of these procedures. The work proposed in this R34 clinical trial planning grant application will allow us to: 1) complete a clinical study protocol and prepare a Multi?Site Manual of Operating Procedures; 2) recruit co?investigators and prepare sites for participation in the U01 study; 3) to develop and conduct a model recruitment protocol; 4) to develop a database for data collection and management; and 5) to determine the best procedure for specimen transfer between participating centers and to determine which cell?specific factors to evaluate. A team of investigators has been recruited which are highly recognized leaders in the treatment of osteonecrosis as well as in the discipline of orthopaedics. The initial sites to be include the Cleveland Clinic, Johns Hopkins University, Lenox Hill Hospital, New York University, Stanford University, University of Minnesota, University of Southern California, and University of Virginia. The study will utilize a centralized radiologist (JHU) as well as an established biostatistical center for data collection and analysis (JHU). Two bone biology laboratories (Cleveland Clinic; Stanford University) will be used to determine the specimen handling and analysis. Based upon our proposed planning activities and our outstanding research team, we will be able to design and finalize the clinical study and prepare the documentation for a successful multi?site trial comparing a promising intervention of treatment for osteonecrosis, cell?based autologous grafting, to our current most often used procedure for osteonecrosis, core decompression.